Hybrid sensor

ABSTRACT

A sensor system and method for analyzing a feature in a sensing volume. The system projecting a pattern onto the feature and imaging the pattern where the pattern intersects with the feature, where the pattern is a series of lines that are encoded to identify at least one line of the series of lines.

PRIORITY AND CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Ser. No.12/474,911, filed May 29, 2009 entitled “Hybrid Sensor”, now U.S. Pat.No. 8,031,345, the contents of which are incorporated herein byreference.

BACKGROUND

1. Field of the Invention

The present invention generally related to sensor system for determiningthe position or orientation of a feature.

2. Description of Related Art

The availability of 3D point cloud data has enabled absolute metrologysystems. There are various modalities through which the 3D data isacquired. Laser scanning and moiré fringe techniques are some of themore popular commercial methods. These two methods produce reliable datain certain circumstances. Laser scanning typically relies on a motiondevice to provide 3D data. Motion can increase the cycle time of ameasurement and may be impractical for many applications. Moiré fringetechniques rely on photogrammetric targets to calibrate and provide 3Ddata. The photogrammetric technique relies on several targets mounted ontop of a sample part to obtain 3D data but produces point cloudinformation without sensor or part translation. However, thesetechniques can require multiple images to solve for the absolute depthand calibration is extensive. In addition, discontinuities in a surfacemay cause sensing problems.

In view of the above, it is apparent that there exists a need for animproved sensor system.

SUMMARY

In satisfying the above need, as well as overcoming the enumerateddrawbacks and other limitations of the related art, the presentapplication provides various sensor system embodiments for analyzing afeature in a sensing volume. In one embodiment, the sensor systemincludes a first laser source, a second laser source, and a sensor. Thefirst laser source projects a laser line into the sensing volume andonto the feature forming a laser stripe on the feature. The sensorimages the laser stripe where the laser line intersects with thefeature. The relationship between the sensor and the first laser sourceis precalibrated, for example in a factory calibration. The second lasersource projects a pattern onto the feature such that the patternintersects the laser stripe on the feature. The sensor uses the laserstripe as a reference depth for the pattern projected by the secondlaser source.

In another embodiment, a sensor system for analyzing a feature in acontiguous sensing volume includes a laser source, a first sensor, and asecond sensor. The laser source being attached to a mounting structureand configured to project a pattern onto the feature forming a laserstripe on the feature. The first sensor being attached to the mountingstructure and configured to image the laser stripe where the laser lineintersects with the feature, the relationship between the first sensorand the first laser source having been precalibrated. The second sensorbeing attached to the mounting structure and configured to image thelaser stripe where the laser line intersects with the feature, therelationship between the second sensor and the first laser source alsohaving been precalibrated. The first sensor having a field of view thatintersects with the pattern projected from the first laser sourceforming a first sensing volume. Similarly, the second sensor having afield of view that intersects with the pattern projected from the firstlaser source forming a second sensing volume. The first and secondsensing volume forming a contiguous sensing volume for the system.

Further objects, features and advantages of this invention will becomereadily apparent to persons skilled in the art after a review of thefollowing description, with reference to the drawings and claims thatare appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a sensor system in accordancewith one embodiment of the invention;

FIG. 2 is a block diagram illustrating a sensor system including astructured light projector;

FIG. 3 is a block diagram of a sensor system illustrating the opticalelements of the laser sources and sensor;

FIG. 4 is a block diagram illustrating a sensor system including a moiréfringe projector;

FIG. 5 is a block diagram illustrating a sensor system including a dualsensor configuration;

FIG. 6 is a block diagram illustrating one embodiment of a system formeasuring features with the disclosed sensor implementations;

FIG. 7 is a block diagram illustrating one embodiment of a system formeasuring wheel alignment with the disclosed sensor implementations;

FIG. 8 is a side view of one embodiment of a system for measuring wheelalignment with the sensor implementation of FIG. 5;

FIG. 9 is a front view of a laser pattern projected onto a tire for oneembodiment of a system for measuring wheel alignment;

FIG. 10 is front view of a laser pattern projected onto a tire for oneembodiment of a system for measuring wheel alignment;

FIG. 11 is front view illustrating various laser pattern implementationsprojected onto a tire for one embodiment of a system for measuring wheelalignment;

FIG. 12 is a flow chart illustrating a method for dynamic imageprocessing window adjustment;

FIG. 13 is a flow chart illustrating a method for dynamic identificationof laser lines;

FIG. 14 is a block diagram of a system illustrative of oneimplementation of the controllers, processors, or modules in the instantapplication; and

FIG. 15 is top view of a mounting structure for a sensor system.

DETAILED DESCRIPTION

Referring now to FIG. 1, a system embodying the principles of thepresent invention is illustrated therein and designated at 10. Thesystem 10 includes sensor 12, a first laser source 14, a second lasersource 16, and a mounting structure 18.

The sensor 12 may comprise receiving optics and a detector such as a CCDor CMOS array. Accordingly, the sensor 12 has a field of view thatprojects outwardly from the camera and a range of focus that is definedby the receiving optics of the sensor. The field of view and depth offocus define a sensing volume of the sensor 12. The first laser source14 may project one or more laser lines. If more than one laser line isprojected from the first laser source 14 the lines may be parallel toone another. In addition, the laser lines may be equally spaced withrespect to each other. The first laser source 14 is oriented at an anglerelative to the sensor such the laser lines intersect the field of viewto define the sensing volume. In one configuration, the laser lines maybe projected such the center laser line intersects the center of thesensing volume. Alternatively, if there are an even number of laserlines, the middle two laser lines may be approximately an equal distancefrom the center of the sensing volume.

The sensor 12 and the first laser source 14 may both be attached to themounting structure 18. The mounting structure 18 may be an opticalbench, tube, or other rigid form. The mounting structure 18 may be madefrom a material with a low coefficient of expansion so that therelationship between the sensor 12 and the first laser source 14 is heldconstant across a wide temperature range. Alternatively, the mountingstructure 18 may include a number of temperature sensors to compensatefor expansion of the mounting structure material. The mounting structure18 may be formed from a number of materials including but not limited tosteel, invar, aluminum, or other industrial materials. For example, themounting structure 18 may be an I-tube (shown as reference numeral 1510in FIG. 15). As such, the mounting structure 18 provides both passivethermal management as well as provides a linear response. The linearresponse without hysteresis enables accurate active thermalcompensation.

The sensor 12 and the first laser source 14 may be factory alignedrelative to one another. For example, the sensor 12 and first lasersource 14 may be mounted onto the mounting structure 18 with the use ofvarious fixtures to control the alignment and/or relative position ofthe sensor 12 and first laser source 14. In addition, the sensor 12 andfirst laser source 14 may be mounted to a precision stage, for examplethrough the mounting structure 18. The precision stage may include aknown target. The known target may be moved throughout the sensingvolume by the precision stage such that the relationship between thesensed position of the target can be calibrated throughout the sensorvolume. The calibration can be stored in the sensor as various sensorsystem model parameters including sensor parameters, laser sourceparameters, etc.

Based on the calibration, the relationship between the sensor 12 and thefirst laser source 14 is known and triangulation may be used todetermine the distance from the sensor 12 to a position where a laserline intersects a feature in the sensing volume. As such, the positionof the feature relative to the sensor 12 can be determined based on thefactory calibration regardless of the orientation or positioning of thesensor 12. Further, a system including many sensors may be formed bydetermining the position and orientation of each sensor relative to amaster coordinate space. This may be done for larger systems by using alaser tracker or theodalites to determine the position and orientationof the sensors directly or by using such devices to determine theposition and orientation of a target in the sensing volume thendetermining a transform between the sensor coordinate space and themaster coordinate space.

A second laser source 16 may also be provided. The second laser source16 may be a laser projector such as a structured light projector or amoiré fringe projector. The second laser source 16 may be mounted to themounting structure 18 or alternatively may be mounted independently ofthe mounting structure 18. If the second laser source 16 is mounted onthe mounting structure 18, the position and orientation of the secondlight source may be factory calibrated similar to the first laser source14. However, often times the geometry of the part or the tooling wherethe part is to be measured may present certain environmental constraintsthat would limit the effectiveness of the second laser source 16 beingmounted to the mounting structure 18. In this scenario, a known targetmay be positioned into the sensing volume and the position of the knowntarget to the sensor may be determined based on a triangulation of thelaser line with the sensor. For example, the laser line may be projectedon a flat surface and the position and orientation of the surfacedetermined based on the position of the laser stripe within the field ofview of the sensor. The second set of lines may then be projected ontothe surface and the orientation and position of the second laser sourcemay be determined based on the projected line pattern on the surface.For example, the spacing and angle of an array of line stripes formed onthe surface intersect with the laser stripe from the first laser source14. The intersection points between the laser stripe and the patternfrom the second laser source 16 can be used to determine the positionand orientation of the second laser source 16.

Therefore, the second laser source 16 may be a structured lightprojector, as depicted in FIG. 2. As discussed, the detector 12 iscalibrated with respect to first laser source 14. As such, these twocomponents work together using triangulation principles. The anglebetween the first laser source 14, thus the laser line, and the opticalaxis of the sensor are used to determine the distance and location offeatures on the surface 20. In, addition the second laser source 16projects a series of lines onto the surface 20. The series of lines 21from the second laser source 16 may be oriented orthogonal to the lineor lines form the first laser source 14. The intersection of the line orlines from the first laser source 14 is used to determine the surfaceposition of the series of lines 21 on the surface from the second lasersource 16. Essentially, the line 22 from the first laser source 14 actsas a reference for the projected pattern from the second laser source16. The surface is then modeled using a camera/optics model. Thecamera/optics model may be generated based on taking a few fieldcalibration images once the sensor is finally mounted using a flatsurface at a number of distances from the sensor. Accordingly, thesecond laser source 16 can be mounted separately from the sensor 12 andfirst laser projector 14, and field calibrated, as described above.

The mechanics of the sensor system of FIG. 1 are further explained withrespect to FIG. 3. The keystoning effect of the structured light patternincreases the depth sensitivity of the measurement. Therefore,projection angle (theta) of second laser source 16 should be designed tobe different than the receiving angle (phi) of the sensor 12. Forexample, the projection angle may be 10 to 15 degrees different than thereceiving angle. To facilitate the key stoning effect, the projectionoptical system 24 of the laser projector 16 may include two lenses 26,28. The additional lens 28 may be used to vary the magnification betweenthe receiving optic 30 and the projection optical system 24.Specifically, the projection optical system 24 may have 1.5-3 times themagnification of the receiving optic 30 within the sensing volume.Although, other ratios may be used, this may provide particular benefitsfor many industrial applications.

Each of the first and second laser sources 14, 16 and the detector 31may be in communication with the sensor controller 29. The sensorcontroller 29 may independently control the time and intensity of eachlaser source 14, 16. In addition, the sensor controller 29 controls theacquisition and integration time of the detector 30. The sensorcontroller 29 may alternate the projection of the first set of laserlines from the first source 14 and the second set of laser lines fromthe second laser source 16. In addition, the detector 31 may besynchronized with the projection of the first and second laser sources14, 16 to capture the first set of laser lines from the first lasersource 14 in the first image and the second set of laser lines from thesecond laser source 16 in a second image.

The second laser source 16 may also be a moiré fringe projector, asillustrated in the system 410 of FIG. 4. The moiré fringe projector mayemit two wavelengths of laser beams that interfere, thereby projecting amoiré fringe pattern 32 onto the surface 20. The moiré fringe pattern 32is like a topographical map with each ring of the fringe patternequating to a different distance from the second laser source 16. Themoiré fringe pattern 16 includes alternating rings of light rings 38 anddark rings 40 that tend to have a sinusoidal profile. Again, the line 22acts as a reference relative to the distance of each of the rings.

Another embodiment of the sensor system is illustrated in FIG. 5. Thesensor system 510 includes a first sensor 511, a second sensor 512, anda laser source 514. The first sensor 511 and second sensor 512 areattached to a mounting structure 518. The first sensor 511 and secondsensor 512 may be CCD, CMOS, or other similar sensors including otherfeatures, such as a sensor controller, as described with regard tosensors of the previous embodiments. The laser source 514 is alsoattached to the mounting structure 518 and is configured to project alaser pattern 534 onto an object. The laser pattern may be any of thepatterns described above, or more specifically, may include a series oflines that are pre-calibrated relative to each of the first sensor 511and second sensor 512. The pre-calibration may be a factory calibrationas described relative to the previous embodiments.

The sensor system 510 has a sensor axis 520 that is substantiallyperpendicular to the optical axis 532 of the laser source 514. A firstsensor 511 is oriented at an angle relative to the sensor axis 520 thatis slightly less than the second sensor 512. For example, the firstsensor 511 may have an optical axis 524 that is oriented at a 17° anglerelative to the sensor axis 520. Further, by way of example, the secondsensor 512 may have an optical axis 528 that is oriented at a 22° anglerelative to the sensor axis 520. As such, the first sensor 511 has afield of view denoted by reference number 526 that intersects with alaser projection 534 to form a sensing volume 521. The axis of the laserprojection 534 may be orthogonal to the sensor axis 520 and may be inplane with the sensor optical axes 528 and 524. Similarly, the secondsensor 512 has a field of view 530 that intersects with the laserprojection 534 to form a second sensing volume 522. The first and secondsensor 511 and 512 are oriented such that the first sensing volume 521and the second sensing volume 522 form a contiguous sensing volume 523.

The first sensing volume 521 slightly overlaps with the second sensingvolume 522 to form the contiguous sensing volume 523. The sensing volume521 is closer to the mounting structure and sensing volume 522 and mostof the sensing volume 521 does not overlap with the sensing volume 522,and similarly most of the sensing volume 522 does not overlap withsensing volume 521. For ease of illustration, the sensing volumes areshown as squares. However, it is clear that the first sensing volume 521and second sensing volume 522 would have an actual 3-D shape formed bythe intersection of the first field of view 526 with the laserprojection 534 and the second field of view 530 with the laserprojection 534, respectively. This shape would, of course, be expandingas the distance increases relative to the sensor or projector and mayhave curved outer regions based on the effects of the optical system. Assuch, the first sensor 511 and the second sensor 512 work togetherthereby greatly increasing the depth of field which can be analyzedwhile providing sufficient resolution for most applications. Further, itis also clear that similar to the previous embodiments, a second lasersource may also be provided and oriented to project a laser pattern tointersect with the first and second sensing volumes 521, 522. Asdiscussed above, the second laser source may be attached to the mountingstructure or mounted independently

In FIG. 6, a measurement system 610 including an array of sensors 614 isprovided. Each sensor 614 corresponds to a sensor system 10, 410 or 510including any variation or combination thereof described above. Thesystem 610 includes a controller 616 and at least one sensor 614. Theremay be a number of sensors 614 located about a vehicle body or frame 612to measure geometric dimensional deviations at a number of specifiedlocations. Alternatively, a single sensor may be used along with amotion device such that the sensor 614 is able to measure multiplefeatures along the vehicle body 612. For example, the sensor 614 may beattached to a robotic arm that can be manipulated to measure a number offeatures at various locations on the vehicle body 612.

The sensor 614 is in electrical communication with the controller 616 toprovide a set of data for each feature measured. The sensor 614 mayinclude an on board processor to analyze the image data and generatefeature data, for example indicating the position and orientation offeature. The feature data may be communicated to the controller 616. Thesensor 614 may communicate with the controller 616 over a number ofwired or wireless communication protocols including but not limited toEthernet. The controller 616 includes a microprocessor configured toanalyze the data. In addition, the controller 616 is in communicationwith an alarm system 618 to generate an alert based on the measurementsfrom the sensor 614. The alarm system 618 may comprise a visualindicator such as a flashing light, an audio indicator such as a siren,or both. In addition, the alarm system 618 may comprise a communicationsystem configured to send an email, phone message, pager message, orsimilar alert.

Now referring to FIG. 7, an inspection system 710 is provided for theinspection of wheel alignment of a vehicle. As such, the inspectionsystem 710 includes two sensor systems 712 which may correspond with anyof the sensor systems 10, 410, or 510 including variations described inthe previous embodiments or combinations thereof. However, forillustrative purposes, the system 710 will be described further withregards to the implementation of the sensor system 510 shown in FIG. 5.As such, the inspection system 710 includes a left sensor 714 thatprojects a laser pattern 726 onto a left side of tire 728. Similarly,inspection 710 includes a right sensor 716 that projects a second laserpattern 724 onto the right sidewall of the tire 728. Accordingly, theleft sensor 714 and the right sensor 716 may determine the position andorientation of both the left sidewall of the tire and right sidewall ofthe tire 728 to determine an overall position and orientation of thetire 728.

The system 710 may be duplicated for each tire on the vehicle andaccordingly a wheel alignment calculation may be performed includingsuch measurements as toe, camber, pitch, etc., for each wheel of thevehicle. The sensor system 712 may be in communication over acommunication link 720 to a controller 722. The communication link 720may include wired or wireless communications including serialcommunications, Ethernet, or other communication mediums. The controller722 may include a processor, memory, and display to perform a wheelalignment measurement. In addition, the controller 722 may be incommunication with other sensor systems 712 measuring other tires orother controllers configured to inspect the alignment of other wheels onthe vehicle.

Now referring to FIG. 8, a side view of the system 810 is providedillustrating one embodiment of the system in FIG. 7 implementing a dualsensor system described in FIG. 5. The sensor system 812 includes afirst sensor 811 a second sensor 812, and a laser source 814. Each ofthe first sensor 811, the second sensor 812, and the laser source 814may be attached to the mounting structure 818. The field of view of eachof the first and second sensor 811, 812 intersect with the laserprojection 834 of the laser source 814 to form a first and secondsensing volume 821, 822. Further, the first sensing volume 821 andsecond sensing volume 822 overlap to form a continuous system sensingvolume 823. As described above in reference to FIG. 5, the contiguoussensing volume 823 allows for increased sensing range between the sensorsystem 712 and the wheel 728.

This increased sensing range denoted by arrow 840 allows for theaccommodation of a large number of tire models and wheel base vehicles,as well as a large steering angle change during a wheel alignmentinspection. Further, the laser source 814 may include optics thatprovide a 1.5 to 3 times magnification relative to the receiving opticsof both the first sensor 811 throughout the first sensing volume 821 andthe second sensor 812 throughout the second sensing volume 822.

Now referring to FIG. 9, a front view of the tire illustrating oneembodiment of the projected laser pattern is provided. In thisembodiment, the left sensor 714 projects a laser pattern 910 including aseries of parallel lines onto the left-hand sidewall of the tire 728.Similarly, the right sensor 716 projects a pattern 912 including aseries of lines onto the right-hand sidewall of the tire 728. Thepattern may include a first set of lines 914 and a second set of lines916, where the first set of lines 914 are parallel and have equalspacing between each consecutive line. Similarly, the second set oflines 916 may have a set of parallel lines where each consecutive linehas equal spacing. Further, the spacing for the second set of lines 916may be the same as the spacing provided in the first set of lines 914.

Now referring to FIG. 10, the first and second set of lines 914 and 916are described in more detail. The first set of lines 914 may include afirst line 1012, a second line 1014, a third line 1016 and a fourth line1018. Further, the second set of lines may have a fifth line 1020, asixth line 1022, a seventh line 1024 and an eighth line 1026. The linesmay have equal spacing as denoted by reference numeral 1032. However,the distance between the fourth line 1018 and the fifth line 1020 mayinclude a greater spacing 1030 as a line identification. The spacing1030 may be, for example, twice the spacing as between the other lines.This may be easily and effectively accomplished by modifying the gratingof a laser line projection source such that the middle two lines of thegrating are not etched but filled in and therefore do not transmitlight. The additional spacing 1030 may be used to identify specific linenumbers in the pattern.

The first sensing volume 821 of the first sensor and the second sensingvolume 822 of the second sensor may have an overlap region 1010 suchthat the double spacing 1030 may be detected by each of the first sensorand second sensor. Accordingly, the overlap 1010 would be great enoughto show the fourth line 1018 in the first sensing volume 821 and thefifth line 1020 in the second sensing volume 822. However, as can bereadily understood, the array of lines may include more than eight linesand as such, the fourth line 1018 and the fifth line 1020 would berepresentative of the middle two lines of the pattern. Using the changein spacing encodes the line pattern and allows the system to easilyidentify the middle two lines, thereby identifying each line within eachsensing volume. After identifying each line, the relationship betweenthe position of the object, in this case the wheel 728 may be determinedusing a sensor model and the predetermined calibration parameters. Thesensor model may include a camera model that accounts for the detectorand optical parameters of the sensor, as well as, a laser source modelthat accounts for the laser pattern and projection objects. Further, thesensor model and laser source model may be linked by the predeterminedcalibration parameters to provide 3D point cloud data on the object.

Now referring to FIG. 11, additional embodiments are provided foridentifying each line in the pattern 912. In one embodiment a secondlaser line 1110 may be provided orthogonal to the series of laser linesfrom a second laser projector. Alternatively, a unique symbol 1112, suchas a crosshair, may be provided in addition to the series of lines thatmay be used to identify each of the lines in the series based on aspacial relationship. In another alternative, each of the middle twolines may have a mark 1114, 1116, such as a cross tick where the crosstick 1114 on the first set of lines 914 is on one side and the crosstick 1116 of the second set of lines 916 is on an opposite side. Assuch, each of the cross ticks is distinguishable and may be used toidentify each of the lines in the series of lines based on the spacialrelationship. In yet another alternative, the spacing between the linesmay vary such that the number of each line may be identified based on avaried spacing relationship between one or more of the consecutivelines. In one example, a double line 1118 may be provided. The two linesmay be provided closely together uniquely identifies one line in theseries of lines and then each of the other lines may be identified by aconsecutive spacial relationship. Further, other identifyingcharacteristics may be provided for encoding the series of consecutivelines including other various unique marks, or line spacing, linethicknesses, or line orientation.

Now referring to FIG. 12, a method for dynamic image processing windowadjustment is provided. A method 1200 starts in block 1210. In block1210, a laser source projects a pattern onto a feature and an image isacquired of the pattern intersecting the feature. In one implementation,the pattern may be the parallel lines 912 in FIG. 9. In block 1212, thelaser signal pixels are extracted from the image. As such, each of thepixels along the line may be transformed into a line intensity profile.As such, a reference line is defined that is substantially orthogonal tothe series of laser lines and may be acquired with temporal offset. Alaser line profile is determined by adding the intensity valueorthogonal to the reference line after correction for sensor and laserprojection distortions by a camera and/or laser projection model. Inblock 1214, high points are identified in the laser profile. Processingzones are computed based on the high points in the profile, as denotedby block 1216. Finally, processing zones are applied and 3D point clouddata is extracted based on general triangulation principles.

Referring to FIG. 13, a method for the dynamic identification andassignment of laser lines is provided. The method 1300 starts in block1310. In block 1310, the laser is projected onto the feature and animage is acquired. In block 1312, the laser signal pixels are extracted.The marker zones in the laser lines are identified as denoted by block1314. The laser line data is projected on to a reference line, athreshold is applied to integrated projected values to identify nodespoints on the laser lines. The node points along the reference line arethen extracted. The reference line may represent the mean location onthe object being measured. The spacing between nodes are then used toidentify line numbers. In one exemplary, the numbering will start fromthe center where we have higher spacing relative to its immediateneighbors. In block 1316, the laser line numbers are assigned based onthe marker zones.

As such, it is understood that the method shown in FIGS. 12 and 13 maybe utilized together in a single process. For example, the marker zonesmay be identified 1314 and laser line numbers assigned 1316 in betweenstep 1216 and the point cloud data being extracted. Further, the abovedescribed methods may be performed by the sensor controller and as suchthe point cloud data may be transmitted from the sensor to the systemcontroller. Alternatively, the system controller may be utilized forimplementing the methods.

Referring to FIG. 15, the mounting structure 18 may be an I-tube 1510.The I-tube includes a tube portion 1512 with an I-beam 1514. Walls 1516extend beyond the I-beam 1514 and form a recess 1520. The laser sourceand detectors may be mounted in the recess 1520 to the I-beam 1514. Inaddition, the I-tube may include cooling fins 1518 to increasedissipation of heat. The I-tube 1510 may be formed from a number ofmaterials including but not limited to steel, invar, aluminum, or otherindustrial materials. The I-tube 1510 may include a number oftemperature sensors to compensate for expansion of the I-tube material.As such, the I-tube 1510 provides both passive thermal management aswell as provides a linear response. The tubular shape and I-beam limitexpansion in directions other than along the length of the tube. Thelinear response without hysteresis enables accurate active thermalcompensation.

Any of the modules, controllers, servers, or engines described may beimplemented in one or more general computer systems. One exemplarysystem is provided in FIG. 14. The computer system 1400 includes aprocessor 1410 for executing instructions such as those described in themethods discussed above. The instructions may be stored in a computerreadable medium such as memory 1412 or a storage device 1414, forexample a disk drive, CD, or DVD. The computer may include a displaycontroller 1416 responsive to instructions to generate a textual orgraphical display on a display device 1418, for example a computermonitor. In addition, the processor 1410 may communicate with a networkcontroller 1420 to communicate data or instructions to other systems,for example other general computer systems. The network controller 1420may communicate over Ethernet or other known protocols to distributeprocessing or provide remote access to information over a variety ofnetwork topologies, including local area networks, wide area networks,the internet, or other commonly used network topologies.

In an alternative embodiment, dedicated hardware implementations, suchas application specific integrated circuits, programmable logic arraysand other hardware devices, can be constructed to implement one or moreof the methods described herein. Applications that may include theapparatus and systems of various embodiments can broadly include avariety of electronic and computer systems. One or more embodimentsdescribed herein may implement functions using two or more specificinterconnected hardware modules or devices with related control and datasignals that can be communicated between and through the modules, or asportions of an application-specific integrated circuit. Accordingly, thepresent system encompasses software, firmware, and hardwareimplementations.

In accordance with various embodiments of the present disclosure, themethods described herein may be implemented by software programsexecutable by a computer system. Further, in an exemplary, non-limitedembodiment, implementations can include distributed processing,component/object distributed processing, and parallel processing.Alternatively, virtual computer system processing can be constructed toimplement one or more of the methods or functionality as describedherein.

Further the methods described herein may be embodied in acomputer-readable medium. The term “computer-readable medium” includes asingle medium or multiple media, such as a centralized or distributeddatabase, and/or associated caches and servers that store one or moresets of instructions. The term “computer-readable medium” shall alsoinclude any medium that is capable of storing, encoding or carrying aset of instructions for execution by a processor or that cause acomputer system to perform any one or more of the methods or operationsdisclosed herein.

As a person skilled in the art will readily appreciate, the abovedescription is meant as an illustration of the principles of thisinvention. This description is not intended to limit the scope orapplication of this invention in that the invention is susceptible tomodification, variation and change, without departing from spirit ofthis invention, as defined in the following claims.

1. A sensor system for analyzing a feature, the sensor systemcomprising: a mounting structure; a first laser source being attached tothe mounting structure and configured to project a pattern into thesensing volume and onto the feature; a first sensor being attached tothe mounting structure and configured to image the pattern where thepattern intersects with the feature, wherein the pattern is a series oflines that are encoded to identify at least one line of the series oflines, each line having an equal spacing with respect to adjacent linesexcept two lines of the plurality of lines having a greater spacingbetween the two lines to serve as a line identification.
 2. The sensorsystem according to claim 1, wherein the pattern is encoded by a uniquespacing between a set of lines in the series of lines.
 3. The sensorsystem according to claim 2, wherein two lines of the series of lineshave a different spacing between the two lines than other lines of theseries of lines.
 4. The sensor system according to claim 3, wherein thetwo lines are in the center of pattern.
 5. The sensor system accordingto claim 3, wherein the other lines have an equal spacing.
 6. The sensorsystem according to claim 5, wherein the spacing between the two linesis at least twice as much as the equal spacing between the other lines.7. The sensor system according to claim 1, wherein first laser sourceincludes a grating, the grating having at least two lines that are notetched to produce a unique spacing in the pattern.
 8. The sensor systemaccording to claim 1, further comprising a processor configured toidentify each line in the series based on the encoding and measure theposition of each line according to the identification.
 9. The sensorsystem according to claim 1, wherein the pattern is encoded by a uniquesymbol projected onto the series of lines.
 10. The sensor systemaccording to claim 9, wherein the unique symbol is a double line. 11.The sensor system according to claim 9, wherein the unique symbol is across tick.
 12. A method for analyzing a feature, the method comprising:projecting a pattern into a sensing volume and onto the feature wherethe pattern of lines is generated by a first laser source; imaging thepattern where the pattern intersects with the feature, wherein thepattern is a series of lines that are encoded to identify at least oneline of the series of lines, each line having an equal spacing withrespect to adjacent lines except two lines of the plurality of lineshaving a greater spacing between the two lines to serve as a lineidentification.
 13. The method according to claim 12, wherein thepattern is encoded by a unique spacing between a set of lines in theseries of lines.
 14. The method according to claim 13, wherein two linesof the series of lines have a spacing between the two lines differentthan a spacing between other lines of the series of lines.
 15. Themethod according to claim 14, wherein the two lines are in the center ofpattern.
 16. The method according to claim 14, wherein the spacingbetween the other lines are equal.
 17. The method according to claim 16,wherein the spacing between the two lines is at least twice the distanceas the spacing between the other lines.
 18. The method according toclaim 12, wherein first laser source includes a grating, the gratinghaving at least two lines that are not etched to produce a uniquespacing in the pattern.
 19. The method according to claim 12, furthercomprising identifying each line in the series based on the encoding andmeasuring the position of each line according to the identification. 20.The method according to claim 12, wherein the pattern is encoded by aunique symbol projected onto the series of lines.